The field of the invention pertains to electric transducers for sensing gaseous flow and proportionally indicating the rate of such flow.
The rate of gas and fluid flow within conduits is often required information in gas and liquid treating systems, such as found in the chemical and petroleum processing arts. Flow meters take a variety of forms employing paddle wheels, propellers, dye and visual devices, and some use the viscosity of the moving medium to produce displacement of indicia means, such as a ball. A common type of visual flow meter displacing a ball wherein increased flow increases ball displacement is shown in Patent 1,889,705.
Difficulty has been encountered in accurately sensing and indicating low rates of gas flow since such low rates and small volumes must overcome the friction of displaceable means to produce gaging, and as many flow meters operate on a resistance principle wherein the resistance of flow about a displaceable member is used to displace the member, relative high rates of flow are usually required in order to produce sensing. Displaceable balls have been used in gas flow meters, as shown in U.S. Pat. No. 2,099.842, and electrical means have also been used in flow gages to indicate the position of the displaceable member as shown in U.S. Pat. No. 3,224,270. Further, a rolling piston has been employed in a flow meter utilizing a variable area outlet as shown in U.S. Pat. No. 1,454,301, and rolling pistons have been used in gas indicators as shown in U.S. Pat. Nos. 3,452,175 and 3,452,309. However, prior art devices have not been of such character as to provide an accurate electrical signal proportional to the rate of low gas flow volume and the present invention has been found to produce superior performance over those devices known to the applicants.